Halve the 2 chicken breasts lengthwise to make 4 thin cutlets. Place each cutlet between sheets of plastic wrap and pound gently to even thickness; pat dry with paper towels.
In a shallow dish, whisk together the flour, 1 teaspoon kosher salt, 1/2 teaspoon black pepper, and 1 teaspoon garlic powder. Dredge each cutlet in the flour mixture and shake off excess.
Heat 1 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium heat until the butter melts. Add the chicken (work in batches if needed) and cook 3–4 minutes per side until golden and nearly cooked through. Transfer to a plate and tent with foil.
If the pan is dry, add 1/2 tablespoon olive oil. Add the minced garlic and sauté about 30 seconds until fragrant. Pour in 1/2 cup chicken stock and deglaze the pan, scraping up browned bits.
Add the heavy cream, drained chopped sun-dried tomatoes, 1/2 teaspoon dried oregano, 1/4 teaspoon dried thyme, and 1/4 teaspoon crushed red pepper (if using). Bring to a simmer over medium-high heat, then reduce to low.
Whisk in 1/2 cup grated Parmesan until melted and the sauce is smooth. Taste and adjust seasoning with salt and pepper as desired.
Return the chicken and any accumulated juices to the skillet. Spoon sauce over the cutlets and simmer 3–4 minutes more until warmed through and the chicken reaches 165°F (74°C).
Remove from heat and garnish with sliced basil if desired, then serve.